This invention relates to a trim eliminator for a log saw and method and, more particularly, to a trim eliminator which can be adjusted quickly to compensate for changes in log length, roll length, trim size and/or roll diameter.
In the production of such consumable products as toilet tissue and kitchen toweling, jumbo sized parent rolls from a paper machine are transferred to a converting area where they are "rewound". The rewinding involves unwinding the parent rolls, usually transversely perforating the web therefrom, and then rewinding the web into a log having the diameter of a retail sized roll. Illustrative of rewinders are co-owned U.S. Pat. Nos. RE. 28,353 and 4,828,195 dealing respectively with the center winding type and the surface winding type of rewinder. The output of these machines normally is a log having a length equal to the width of the web being unwound from the parent roll.
Thereafter, this log is subjected to transverse cutting by a log saw so as to develop a plurality of retail sized rolls and to end trim annuli. Illustrative of a log saw is co-owned U.S. Pat. No. RE. 30,598. The annuli at the log ends are necessarily present because the width of the sheet or web from the parent roll cannot be exactly an even multiple of the number of rolls to be derived therefrom. A certain amount of "trim" is always provided so as to make sure that the end rolls, i.e., the rolls from each side of the web, have clean, flat ends.
The trim annuli have been disposed of over the years in a number of ways. The first ways used belt and rail systems that allowed the trims to fall through the rails based on the length to width ratio of the cut rolls. This type removed a high percentage of the trim annuli but was not perfect. In the early days, machine speeds were slower and roll wrapping less automatic so the operation was more tolerant of trims which could be removed from the operating area in other ways.
As wrapping equipment became fully automated, producers could no longer tolerate any trims getting past the trim eliminator area of the log saw. In recent years, the trim eliminator made use of an overhead chain conveyor with fingers on a certain pitch (i.e., spacings) that grabbed and controlled the rolls coming out of the saw and conveyed them over a wide opening over a cull conveyor. The controlled rolls were then delivered to a secondary roll transport conveyor for direct feed into a downstream wrapper. Currently, two methods are employed to separate the trims from the good rolls. First, the finger-equipped overhead conveyor has fingers missing in the area corresponding to known trim locations and the trim falls off into the cull unit. Second, all fingers are present but the fingers that would have the opportunity to grab trims are opened over the cull area.
There are shortcomings of the current systems in that fingers are susceptible to breakage during jams, the fingers and cam operators are considered a high maintenance item, the finger roll diameter range is not always adequate and the fingers' constant pitch (spacing) requires that the incoming rolls are also on a constant pitch. This means that if the cutoff length is changed (a new roll pitch or length), the roll pitch between logs also changes making the fingers end up out of phase with the rolls. Related to this type of trim handling mechanism is co-owned U.S. Pat. No. 4,977,803. The problem of phase differences because of the change in roll and/or log lengths has been addressed with servo drives on the finger conveyor but this has still not provided the solution desired by producers of toilet tissue and toweling.
According to the invention, a novel type of roll suspension means is provided consisting of two suspension conveyor systems for each log lane which can be readily "phased" to compensate for changes in roll diameter and/or the length of the roll, trim and log. The term log as used herein refers not only to convolutely wound webs but also to any elongated lengths of multi-ply material such as interfolded facial tissues which require end trimming when transversely severed to provide shorter lengths.
More particularly, the invention provides a method and apparatus for handling rolls and trim annuli resulting from transversely severing logs of convolutely wound web material such as toilet tissue and kitchen toweling wherein each log has an upstream end and a downstream end. The apparatus includes a frame, trough means on the frame defining a horizontal path also having upstream and downstream ends for supporting first the logs and thereafter the rolls. Pusher means are operably associated with the trough means for engaging the upstream end of a log to advance the log toward the downstream end of said path. Blade means are movably mounted on the frame for transversely severing each log into a plurality of retail-size rolls and upstream and downstream trim annuli.
The trough means adjacent the path downstream end is equipped with means for opening the trough to remove the support from the retail-size rolls and trim annuli with the opening means having a horizontal length sufficient to allow a trim annulus to fall through the trough means More particularly, the opening means has a horizontal length sufficient to open at least one cut roll length.
There are first means mounted on the frame above the opening means for suspending the first log upstream roll and second means above the opening for suspending the following log downstream roll independently of the first log upstream roll, neither of the first and second means being operative to suspend the trim annuli whereby the trim annuli are adapted to fall out of the path.
In the preferred embodiment, the roll suspending means includes a pair of belt systems, each equipped with foraminous pad portions which are subjected to vacuum so as to support at least the upstream roll of a given log and at least the downstream roll of a following log. Means are also provided for changing the relationship of one pad relative to the other whenever there is a "length" change, i.e., a change in length of the roll, the log and/or the trim annulus.
Other objects and advantages of the invention may be seen in the details of construction set down in the ensuing specification.